Dragline including improved walking mechanism

ABSTRACT

A dragline comprising a main housing, a bucket hoist mechanism mounted on the housing, a bucket drag mechanism mounted on the main housing, a walking mechanism for moving the main housing over the ground, the walking mechanism including a motor mounted on the main housing, a planetary transmission which is mounted on the main housing and which is driven by the motor, a transmission output shaft driven by the transmission, a walk leg housing connected to the output shaft via an output pinion, a driven gear, and a driven eccentric such that rotation of the output shaft causes walking movement of the walk leg housing, and a shoe fixed to the walk leg housing for engaging the ground during walking movement of the walk leg housing, a boom extending from the main housing, a bucket, a hoist rope extending between the bucket and the bucket hoist mechanism and over the sheave for causing vertical movement of the bucket, and a drag rope extending between the bucket and the bucket drag mechanism for causing horizontal movement of the bucket.

BACKGROUND OF THE INVENTION Field of the Invention

The invention relates to a walking mechanism for draglines. Discussionof Prior Art

A walking dragline typically includes a main housing and a boom whichextends upwardly and outwardly from the main housing and has thereon asheave for supporting a hoist rope. The hoist rope extends from a buckethoist mechanism and over the sheave to a bucket for causing verticalmovement of the bucket. A drag rope extends between a bucket dragmechanism and the bucket for causing horizontal movement of the bucket.The main housing is supported by a tub that sits on the ground when thedragline is engaged in digging operations. A pair of walking mechanismsare mounted on the opposite sides of the main housing and are operablefor moving the main housing over the ground between digging operations.An overhead crane is mounted in the interior of the main housing forlifting and moving components for repairs.

U.S. Pat. No. 5,245,882 discloses a walking mechanism of ordinaryconstruction. A walking mechanism ordinarily includes a shoe forengaging the ground during walking movement. The shoe is fixed to a walkleg housing which is mounted on an eccentric and which is connected by aknee link to the main housing, such that rotation of the eccentriccauses the walk leg housing to pivot, thereby causing walking movementof the shoe. The eccentric is fixed to a main walk shaft and rotates atabout one revolution per minute. The main walk shaft is driven by alarge diameter driven gear which is spline fit to the main walk shaft.The driven gear is driven by an output pinion mounted on the outputshaft of a large gear box. The gear box is driven by a large motor.

SUMMARY OF THE INVENTION

On one known dragline, the walking mechanism gear box is mounted on themain surface or floor of the main housing adjacent the driven gear, andis so large that it reduces access to the driven gear, the main walkshaft, the eccentric and the walk leg housing with the overhead crane,and thus increases the difficulty of repairing these components. Alsobecause the gear box is so large, the large motor is elevated far abovethe floor of the main housing. Further, the gear box and motor must beaccessed from elevated platforms constructed specifically for thispurpose. The gear box components typically are exposed for lubrication.Also, the gear boxes for the walking mechanisms on opposite sides of themain housing are not interchangeable, so different gear boxes must beconstructed for each walking mechanism.

The invention provides an improved moving mechanism for a dragline.Preferably, the moving mechanism includes a walking mechanism.Specifically, the walking mechanism includes a motor which is fixed tothe main housing floor. The walking mechanism also includes a cradlewhich is mounted on the main housing floor. The walking mechanismincludes a pedestal which is spaced from the cradle and which is fixedto the main housing floor. The pedestal includes an inboard leg havingtherein an inboard bore and an outboard leg having therein an outboardbore. The outboard leg includes a base portion which extends upwardlyfrom the main housing floor and defines the lower half of the outboardbore. The outboard leg also includes a cap portion removably fixed tothe base portion. The cap portion defines the upper half of the outboardbore.

The walking mechanism includes a planetary transmission supported by thecradle and by the pedestal, as described below. The transmission has ahorizontal center axis and includes an input shaft which is generallycoaxial with the motor output shaft. A spacer coupling releasably anddrivingly connects the motor output shaft to the transmission inputshaft. The transmission includes an input end housing supported by thecradle. A reduction gear is rotatably supported by the input end housingand is driven by an input pinion fixed to the input shaft. A first sungear is fixed to the reduction gear for common rotation therewith aboutthe center axis of the transmission. First planet gears mesh with thefirst sun gear and a first ring gear and thus revolve about the firstsun gear and the center axis. A first carrier is connected by pins tothe first planet gears and thus rotates about the center axis. A secondsun gear is fixed to the first carrier for common rotation therewithabout the center axis. Second planet gears mesh with the second sun gearand a second ring gear and thus revolve about the second sun gear andthe center axis. A second carrier is connected by pins to the secondplanet gears and thus rotates about the center axis. The transmissionalso includes a pilot member which is fixed to the second ring gear,which extends into the inboard bore of the pedestal, and which issupported by the inboard leg of the pedestal.

The walking mechanism includes an output shaft which is centered on thecenter axis. The inner end of the output shaft is spline fit to thesecond carrier and rotatably supported by the transmission, and theouter end of the output shaft is rotatably supported by a bearingcapsule housed in the outboard bore in the outboard leg of the pedestal.An output pinion is fixed to the output shaft for common rotationtherewith about the center axis. The outer diameter of the output pinionis less than the inner diameter of the outboard bore in the outboard legof the pedestal. The bearing capsule and the output shaft having theoutput pinion thereon thus can be removed from the pedestal by movingthe output shaft and pinion away from the transmission in the directionalong the center axis and through the outboard bore, without removingthe cap portion from the base portion of the outboard leg and withoutremoving the transmission from the pedestal. The bearing capsule, theoutput shaft and the output pinion can also be removed from the pedestalby removing the cap portion of the pedestal, moving the output shaft andpinion away from the transmission to disconnect the output shaft fromthe second carrier, and lifting the bearing carrier, the output shaftand the output pinion.

The walking mechanism includes a driven gear which is driven by theoutput pinion. The driven gear is fixed to a main walk shaft and isrotatably supported on the main housing for rotation about a generallyhorizontal axis. A driven eccentric also is fixed to the main walk shaftfor common rotation therewith. A walk leg housing is connected to a kneelink and to the driven eccentric such that rotation of the driveneccentric causes walking movement of the walk leg housing. A shoe isfixed to the walk leg housing for engaging the ground during walkingmovement of the walk leg housing.

It is advantageous that the transmission can readily be removed from thecradle and pedestal with the overhead crane without also removing themotor from the main housing floor. Specifically, the transmission can beremoved by disconnecting the spacer coupling between the motor outputshaft and the transmission input shaft, disconnecting the transmissionfrom the cradle and the pedestal, and moving the transmission toward themotor to remove the pilot member from the inboard bore of the pedestal.The transmission must also be moved far enough to disconnect thetransmission output shaft from the second carrier, or else the outputshaft must be moved away from the motor far enough to disconnect thetransmission output shaft from the second carrier. Thereafter, thetransmission can be lifted away from the cradle and the pedestal.

It is an advantage that the output shaft can be removed from thetransmission and the outboard bore of the pedestal either by moving theoutput shaft and output pinion away from the transmission and outwardlythrough the outboard bore, or by removing the cap portion from the baseportion of the outboard leg, moving the output shaft away from thetransmission to disconnect the output shaft from the second carrier, andthen moving the output shaft upwardly away from the base portion of theoutboard leg.

It is a further advantage that the output shaft and output pinion areremovable without removing the driven gear from the main walk shaft.

It is an advantage that the transmission and motor are mounted on themain housing floor and can be accessed for repairs and maintenance bypersonnel standing on the main housing floor.

It is also an advantage that the driven gear, the main walk shaft, theeccentric and the walk leg housing can be reached and lifted with acrane.

It is advantageous that the input end housing, the first ring gear, thesecond ring gear, and the pilot member together comprise a fluid-tighthousing of the transmission. The housing contains lubrication fluid inwhich the internal components of the transmission are immersed.

It is a further advantage that the transmission is suitable for use inboth walking mechanisms of the dragline. The transmission is simplyrotated about its center axis when used on the opposite side of thedragline.

Other features and advantages of the invention will become apparent tothose skilled in the art upon review of the following detaileddescription, claims and drawings.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevational view of a dragline embodying the invention.

FIG. 2 is a partial perspective view of the main housing.

FIG. 3 is a partial top plan view of the main housing.

FIG. 4 is an enlarged portion of FIG. 3.

FIG. 5 is an enlarged portion of FIG. 1.

FIG. 6 is a view taken generally along line 6--6 in FIG. 4, with partsremoved for clarity.

FIG. 7 is a view taken generally along line 7--7 in FIG. 6.

FIG. 8 is a view taken generally along line 8--8 in FIG. 4.

Before one embodiment of the invention is explained in detail, it is tobe understood that the invention is not limited in its application tothe details of the construction and the arrangements of components setforth in the following description or illustrated in the drawings. Theinvention is capable of other embodiments and of being practiced orbeing carried out in various ways. Also, it is to be understood that thephraseology and terminology used herein is for the purpose ofdescription and should not be regarded as limiting.

DESCRIPTION OF THE PREFERRED EMBODIMENT

A dragline 10 embodying the invention is illustrated in the drawings.The dragline 10 comprises (FIG. 1) a main housing 12 including anoperator's cab 14. The main housing 12 also includes (FIGS. 2-6) anupwardly facing deck or main housing floor 16. The main housing 12 alsoincludes (FIGS. 2 and 3) a lifting apparatus 18 which is supported abovethe main housing floor 16 for lifting and moving components above themain housing floor 16 for repair and maintenance. In the illustratedembodiment, the lifting apparatus 18 comprises a pair (one shown in FIG.3) of overhead cranes on the opposite sides of the main housing 12. Eachof the overhead cranes 18 includes a bridge which is movable along apair of rails, a trolley which is mounted on the bridge and which ismovable along the bridge perpendicular to the rails, and a hoist whichis mounted on the trolley and which is operable for lifting componentsabove the main housing floor 16. The dragline 10 also includes (FIGS.1-3) a bucket hoist mechanism 20 and a bucket drag mechanism 22, both ofwhich are mounted on the main housing 12. Referring to FIG. 1, a boom 24extends upwardly and outwardly from the main housing 12. The upper endof the boom 24 has thereon a sheave 26. The boom 24 is supportedrelative to the main housing 12 by conventional supporting structure 28.The dragline 10 also includes a bucket 29, a hoist rope 30 extendingbetween the bucket hoist mechanism 20 and the bucket 29 and over thesheave 26 for causing vertical movement of the bucket 29, and a dragrope 31 extending between the bucket drag mechanism 22 and the bucket 29for causing horizontal movement of the bucket 29. The dragline 10further includes (FIGS. 1 and 5) a tub 32 which sits on the ground andthus supports the main housing 12 during digging operations. Thedragline 10 also includes (shown best in FIGS. 1-5) a moving mechanism34, further described below, which moves the main housing 12 over theground between digging operations.

In the illustrated embodiment (FIGS. 1-3 and 5), the moving mechanism 34comprises a pair of walking mechanisms 36 and 38. In another embodiment(not shown) the moving mechanism can be another mechanism, such as a setof crawler tracks, which is suitable for moving the dragline over theground. When operated in unison, the walking mechanisms 36 and 38 liftthe main housing 12 and tub 32 and move them a short distance. In thespecific embodiment illustrated, the walking mechanisms 36 and 38 movethe main housing about seven feet in each so-called "step". The walkingmechanisms 36 and 38 are mirror images, and only the walking mechanism36 will be described in further detail.

The walking mechanism 36 includes (FIGS. 2-4 and 6) a motor 40. In theillustrated embodiment, the motor 40 is an electric motor. In anotherembodiment (not shown), the motor can be an internal combustion engine.The motor 40 includes an output shaft 41. The output shaft 41 isrotatable about a generally horizontal axis 42. The motor 40 alsoincludes a motor housing 43. The motor housing 43 includes (FIG. 6) apair of mounting bars 44 (one shown). Each of the mounting bars 44 isfixed to the main housing floor 16 by a set of bolts 45. The motor 40thus is fixed to the main housing floor 16.

The walking mechanism 36 includes (FIGS. 4 and 6) a cradle 46 which ismounted on the main housing floor 16. The cradle 46 includes a U-shapedbase or lower portion 48 which is fixed to the main housing floor 16 bybolts 50. The cradle 46 also includes a vertical mounting plate 52 (seeFIG. 6) which extends upwardly from the lower portion 48. The cradle 46also includes a pair of plate gussets 53 (FIGS. 4 and 6) which arewelded to the lower portion 48 and to the mounting plate 52 to providesupport for the mounting plate 52.

The walking mechanism 36 includes (FIGS. 4 and 6-7) a pedestal 54 whichis spaced from the cradle 46. The pedestal 54 includes a base plate 55fixed to the main housing floor 16 by bolts 56. The pedestal 54 includesan inboard leg 58 which extends upwardly from and is welded to the baseplate 55. The inboard leg 58 has therein (FIG. 6) a circular inboardbore 60 which extends horizontally and which is centered on a horizontalaxis 61. The pedestal 54 also includes (FIGS. 4 and 6) an outboard leg64 which is spaced in the outboard direction (e.g. in the direction awayfrom the motor 40) from the inboard leg 58. The outboard leg 64 includes(FIGS. 6 and 8) a base portion 70 which is welded to the base plate 55and which is fixed to the main housing floor 16 by bolts 71. The baseportion 70 extends upwardly from the main housing floor 16 and definesthe lower half of a circular outboard bore 76 which extendshorizontally. The outboard leg 64 also includes (FIGS. 4 and 6) a capportion 78 which is removably fixed to the base portion 70 by bolts 80.The cap portion 78 defines the upper half of the outboard bore 76. Whenthe cap portion 78 is fixed to the base portion 70, the cap portion 78and base portion 70 cooperate to define (FIG. 6) the outboard bore 76.The outboard bore 76 is centered on the axis 61. The pedestal 54 furtherincludes (FIGS. 4 and 6-8) brace plates or members 82 welded to the baseplate 55, the inboard leg 58 and the outboard leg 64 to provide supportfor the inboard and outboard legs 58 and 64.

The walking mechanism 36 includes (FIGS. 2-7) a planetary transmission85. The transmission 85 has (FIGS. 3-4 and 6-7) a generally horizontalcenter axis 86 coaxial with the axis 61. The transmission 85 includes aninput shaft 88 which is generally coaxial with the motor output shaft 41and which is rotatable about the axis 42. A spacer coupling 90releasably and drivingly connects the motor output shaft 41 to thetransmission input shaft 88. The spacer coupling 90 includes a first hub91 which is releasably connected to the motor output shaft 41, a secondhub 92 which is releasably connected to the transmission input shaft 88,and a center member or spacer 93 releasably connected between the firstand second hubs 91 and 92. The spacer coupling 90 thus drivinglyconnects the motor output shaft 41 to the transmission input shaft 88.The spacer 93 is removable such that the transmission 85 is moveableinwardly toward the motor 40.

The transmission 85 includes (FIGS. 6-7) an input end housing 104 whichis mounted on the mounting plate 52 of the cradle 46 (shown in FIG. 6)by bolts 106. The input end housing 104 supports (FIG. 6) inner andouter bearings 108 and 110 which in turn rotatably support thetransmission input shaft 88. A sealing cap 112 (FIGS. 6-7) surrounds thetransmission input shaft 88 and is fixed to the input end housing 104 bysuitable means such as bolts or screws (not shown).

The transmission 85 includes (FIGS. 4 and 6-7) an input pinion 122 fixedto the input shaft 88 for common rotation therewith about the axis 42.The input pinion 122 can either be integral with the input shaft 88 orbe fixed to the input shaft 88 such as by splines.

The transmission 85 also includes a reduction gear 128 supported forrotation about the center axis 86. The reduction gear 128 includes (FIG.6) a central hub portion 130, a web 131 extending radially outwardlyfrom the hub portion 130, and gear teeth 132 extending radiallyoutwardly from the web 131. The hub portion 130 is rotatably supportedby inner and outer bearings 134 and 136 (FIG. 6). The inner bearing 134is supported by a bearing support member 138, and the outer bearing 136is seated in a bore 139 in the input end housing 104. The bearingsupport member 138 is fixed to the input end housing 104 by suitablemeans such as bolts or screws (not shown). A sealing cap 140 closes thebore 139 in the input end housing 104.

The transmission 85 includes (FIGS. 4 and 6-7) a first sun gear 142. Thesun gear 142 includes a shaft portion 144 spline fit to the hub of thereduction gear 128. The sun gear 142 thus is fixed to the reduction gear128 for common rotation therewith about the center axis 86. The sun gear142 also includes a toothed portion 146 which is integral with the shaftportion 144.

The transmission 85 includes (FIGS. 6-7) a first ring gear 152. The ringgear 152 is fixed to the input end housing 104 by suitable means such asbolts or screws (not shown). The ring gear 152 includes radiallyinwardly extending gear teeth 164. The ring gear 152 is centered on thecenter axis 86.

The transmission 85 includes (FIGS. 6-7) four identical first planetgears 166 (two shown). The planet gears 166 are spaced equidistant fromone another about the sun gear 142. Each planet gear 166 meshes with thesun gear 142 and with the ring gear teeth 164. The planet gears 166 thusare driven by the sun gear 142 and revolve around the sun gear 142 andthe center axis 86.

The transmission 85 includes (FIGS. 6-7) a first carrier 172. Thecarrier 172 has a central bore 178 which extends horizontally and whichis centered on the center axis 86. Each of the planet gears 166 isdrivingly connected to the carrier 172 by a respective pin 192. Each pin192 supports a bearing 194 (FIG. 6) which in turn rotatably supports therespective planet gear 166. Each pin 192 is housed in and extends from arespective bore in the carrier 172. The carrier 172 thus is connected tothe planet gears 166 by the pins 192 such that revolution of the planetgears 166 around the center axis 86 causes rotation of the carrier 172about the center axis 86.

The transmission 85 includes (FIGS. 6-7) a second sun gear 198. The sungear 198 includes a shaft portion 200 which is housed in the carrierbore 178 and which is spline fit to the carrier 172. The sun gear 198thus is fixed to the carrier 172 for common rotation therewith about thecenter axis 86. The sun gear 198 also includes a toothed portion 202which is integral with the shaft portion 200.

The transmission 85 includes (FIGS. 4 and 6-7) a second ring gear 210.The ring gear 210 is fixed to the ring gear 152 by suitable means suchas bolts or screws (not shown). The ring gear 210 includes (FIGS. 6-7)radially inwardly extending gear teeth 222. The ring gear 210 iscentered on the center axis 86.

The transmission 85 includes (FIGS. 4 and 6-7) four identical secondplanet gears 224 (two shown). The planet gears 224 are spacedequidistant from one another about the sun gear 198. Each planet gear224 meshes with the sun gear 198 and with the ring gear teeth 222. Theplanet gears 224 thus are driven by the second sun gear 198 and revolvearound the second sun gear 198 and the center axis 86.

The transmission 85 includes (FIGS. 6-7) a second carrier 234. Thecarrier 234 has a central bore 244 which extends horizontally and whichis centered on the center axis 86. Each of the planet gears 224 isdrivingly connected to the carrier 234 by a respective pin 246. Each pin246 supports bearings 248 which in turn rotatably support the respectiveplanet gear 224. Each pin 246 is housed in a respective pair of spacedbores in the carrier 234. The carrier 234 thus is connected to theplanet gears 224 by the pins 246 such that revolution of the planetgears 224 around the center axis 86 causes rotation of the carrier 234about the center axis 86.

The transmission 85 includes (FIGS. 4 and 6-7) a pilot member 276. Thepilot member 276 includes an annular projection 282 which surrounds thecarrier 234 and which is housed in the inboard bore 60 of the inboardleg 58 of the pedestal 54. The annular projection 282 supports (FIGS.6-7) a bearing 286 which in turn rotatably supports the carrier 234. Thepilot member 276 also includes an annular flange 288 which extendsradially outwardly from the annular projection 282. The annular flange288 is fixed to the ring gear 210 by a set of circumferentially spacedbolts 289 and is fixed to the inboard leg 58 by a set ofcircumferentially spaced bolts 290. The inboard leg 58 of the pedestal54 thus supports the pilot member 276 and thereby the transmission 85above the main housing floor 16.

The walking mechanism 36 includes (FIGS. 3-4 and 6-8) an output shaft292 which is centered on the center axis 86. The output shaft 292includes (FIGS. 4 and 6) opposite inner and outer or right and leftends. The inner or right end (FIGS. 6 and 7) extends into the carrierbore 244 and is spline fit at 294 to the carrier 234. The output shaft292 thus is fixed to the carrier 234 for common rotation therewith aboutthe center axis 86. The output shaft 292 is selectively releasable fromthe carrier 234 by moving the inner or right end away from and out ofthe carrier 234 in the direction along the center axis (to the left inFIG. 6), as further described below.

The walking mechanism 36 includes (FIGS. 2-6 and 8) an output pinion312. The output pinion 312 is fixed to the output shaft 292 intermediatethe ends for common rotation therewith about the center axis 86. Theoutput pinion 312 can either be integral with the output shaft 292 or befixed to the output shaft 292 such as by splines. The output pinion 312has an outer diameter less than the inner diameter of the outboard bore76.

The walking mechanism 36 includes (FIGS. 4, 6 and 8) a bearing capsule322 which is supported in the outboard bore 76. The bearing capsule 322includes (FIG. 6) an annular outer wall 326 which abuts the outboard leg64. The outer wall 326 has thereon a radially outwardly extending flange327 abutting the outboard leg 64. A set of bolts 333 extend through theradial flange 327 and into the outboard leg 64. The bearing capsule 322thus is removably housed in the outboard bore 76. The bearing capsule322 also includes a cover plate 328 which is attached to the outer wall326 by bolts 334. The outer wall 326 and cover plate 328 cooperate todefine a bearing cavity. The bearing cavity contains a bearing 336centered on the center axis 86. The outer end of the output shaft 292 isreceived in the bearing cavity and is rotatably supported by the bearing336. The output shaft 292 thus is rotatably supported by the outboardleg 64 of the pedestal 54 and by the carrier 234 for rotation about thecenter axis 86.

The components of the walking mechanism 36 as hereinafter described areas set forth in detail in U.S. Pat. No. 5,245,882, which is herebyincorporated by reference.

The walking mechanism 36 includes (FIGS. 4 and 8) a main walk shaft 346.The main walk shaft 346 is rotatably supported on the main housing 12for rotation about a generally horizontal axis 358. A driven gear 362(FIGS. 2-5 and 8) is fixed to the main walk shaft 346 for commonrotation therewith about the axis 358. The driven gear 362 thus isrotatably supported by the main housing 12 for rotation relative theretoabout the axis 358. The driven gear 362 meshes with and is driven by theoutput pinion 312.

The walking mechanism 36 includes (FIG. 5) a driven eccentric 378 whichis fixed to the main walk shaft 346 for common rotation therewith aboutthe axis 358. The driven eccentric 378 thus is driven by the driven gear362 and is supported by the main housing 12 for rotation relativethereto about the axis 358.

The walking mechanism 36 includes (FIGS. 4 and 5) a knee link 382. Oneend of the knee link 382 is pivotally connected to the main housing 12.A walk leg housing 394 is connected to the other end of the knee link382 and to the driven eccentric 378 such that rotation of the driveneccentric 378 causes walking movement of the walk leg housing 394.

The walking mechanism 36 includes (FIGS. 1-2 and 5) a shoe 398. The shoe398 is fixed to the walk leg housing 394 for engaging the ground duringwalking movement of the walk leg housing 394.

In operation of the walking mechanism 36 to move the main housing 12across the ground, the motor 40 is operated to cause rotation of themotor output shaft 41 and thus drive the transmission input shaft 88.The input pinion 122 rotates in common with the input shaft 88 anddrives the reduction gear 128. The sun gear 142 rotates in common withthe reduction gear 128 and drives the planet gears 166 to revolve aroundthe sun gear 142 and inside the ring gear 152. The planet gears 166 areconnected to the carrier 172 via the pins 192 and thus drive the carrier172. The sun gear 198 rotates in common with the carrier 172 and drivesthe planet gears 224 to revolve around the sun gear 198 and inside thering gear 210. The planet gears 224 are connected to the carrier 234 viathe pins 246 and thus drive the carrier 234. The output shaft 292rotates in common with the carrier 234. The output pinion 312 rotates incommon with the output shaft 292 and drives the driven gear 362. Thedriven gear 362 is fixed to and drives the main walk shaft 346 and thusdrives the driven eccentric 378. Rotation of the driven eccentric 378causes walking movement of the walk leg housing 394. The shoe 398 moveswith the walk leg housing 394 and engages the ground for lifting andmoving the main housing 12.

When it is necessary to remove the transmission 85 for repair orreplacement, the transmission 85 can readily be removed from the cradle46 and pedestal 54 with the overhead crane 18. The transmission 85 canbe removed by removing the spacer 93 and thus disconnecting thetransmission input shaft 88 from the motor output shaft 41, removing thebolts 290 connecting the pilot member 276 to the pedestal 54, removingthe bolts 50 securing the cradle 46 to the main housing floor 16, andmoving the transmission 85 and the cradle 46 toward the motor 40 (to theright in FIG. 6) to remove the annular projection 282 of the pilotmember 276 from the inboard bore 60 of the pedestal 54. Also, thetransmission must be moved far enough to disconnect the transmissionoutput shaft 292 from the second carrier 234, or the output shaft 292must be moved in the opposite direction (to the left in FIG. 6) farenough to disconnect the transmission output shaft 292 from the secondcarrier 234. Once the transmission is clear of both the pedestal 54 andthe output shaft 292, the transmission 85 and the cradle 46 can belifted away from the pedestal 54. Alternatively, rather thandisconnecting the cradle 46 from the floor 16, the transmission 85 couldbe disconnected from the cradle 46 (by removing the bolts 106) and thenmoved relative to the cradle 46. This is not preferred, however, becauseit is easier to move the cradle 46 with the transmission 85 than to movethe transmission 85 relative to the cradle 46.

The output shaft 292 can be removed from the central bore 244 of thesecond carrier 234 by two different methods. According to a firstmethod, the bolts 333 are removed from the outboard leg 64 and from theradial flange 327 of the bearing capsule 322, and the bearing capsule322 and the output shaft 292 are moved outwardly (to the left in FIG. 6)along the center axis 86 and through the outboard bore 76. The outputshaft 292 thus can be disconnected from the second carrier 234 bypulling the output shaft 292 and the output pinion 312 through theoutboard bore 76, without removing the cap portion 78 from the baseportion 70 of the outboard leg 64.

A second method for removing the output shaft 292 is to remove the bolts333 from the outboard leg 64 and from the radial flange 327 of thebearing capsule 322, remove the cap portion 78 from the base portion 70of the outboard leg 64, move the bearing capsule 322 and the outputshaft 292 outwardly along the center axis 86 to disengage the outputshaft 292 from the second carrier 234, and then lift the bearing capsule322, the output shaft 292 and the output pinion 312 away from the baseportion 70 of the outboard leg 64. The output shaft 292 and outputpinion 312 thus are removable without removing the transmission 85 fromthe cradle 46 and pedestal 54, and without removing the driven gear 362from the main walk shaft 346.

The transmission 85 and motor 40 are mounted on the main housing floor16 and can be accessed for repairs and maintenance by personnel standingon the main housing floor 16, so elevated platforms are not required.The driven gear, the main walk shaft, the eccentric and the walk leghousing can be reached and lifted with a crane.

The input end housing 104, first ring gear 152, second ring gear 210 andpilot member 276 together comprise a fluid-tight housing of thetransmission 85. The housing contains lubrication fluid in which theinternal components of the transmission 85 are immersed. The componentsof the transmission 85 thus are not exposed for external lubrication.

The transmission 85 is suitable for use in either walking mechanism 36or 38. More particularly, the input shaft 88 is positioned in a desiredposition by rotating the transmission 85 about the center axis 86 andthen mounting the transmission 85 in the desired orientation. The outputshaft 292 is centered on the center axis 86, and the position of theoutput shaft 292 thus is not affected by rotating the transmission aboutthe center axis 86.

Various features of the invention are set forth in the following claims.

What is claimed is:
 1. A dragline comprisinga main housing having agenerally horizontal, upwardly facing surface, a bucket hoist mechanismmounted on said housing, a bucket drag mechanism mounted on said mainhousing, a walking mechanism for moving said main housing over theground, said walking mechanism includinga motor mounted on said mainhousing, a planetary transmission which is mounted on said main housingand which is driven by said motor, a transmission output shaft driven bysaid transmission, a walk leg housing connected to said output shaftsuch that rotation of said output shaft causes walking movement of saidwalk leg housing, and a shoe fixed to said walk leg housing for engagingthe ground during walking movement of said walk leg housing, a boomextending from said main housing, a bucket, a hoist rope extendingbetween said bucket and said bucket hoist mechanism and over said sheavefor causing vertical movement of said bucket, a drag rope extendingbetween said bucket and said bucket drag mechanism for causinghorizontal movement of said bucket, a pedestal fixed to said mainhousing floor, said pedestal including a leg extending upwardly, saidleg having therein a circular bore, and a pilot member including anannular projection housed in said bore, said pilot member being fixed tosaid transmission.
 2. A dragline as set forth in claim 1 wherein saidpilot member also includes an annular flange extending radiallyoutwardly from said annular projection, said flange being fixed to saidpedestal and to said transmission.
 3. A dragline as set forth in claim 1and further comprising a cradle fixed to said planetary transmission andto said main housing for supporting said transmission above said mainhousing floor.
 4. A dragline as set forth in claim 1 wherein said motorincludes an output shaft rotatable about a generally horizontal axis,wherein said transmission has a generally horizontal center axis, andwherein said dragline further comprises a planetary transmission inputshaft which is generally coaxial with said motor output shaft and whichdrives said transmission, and a spacer drivingly connecting said motoroutput shaft to said planetary transmission input shaft.
 5. A draglineas set forth in claim 4 wherein said spacer is removable from said motoroutput shaft and from said transmission input shaft such that saidtransmission is moveable inwardly toward said motor to disengage saidpilot member from said bore so that said transmission can thereafter belifted relative to said main housing floor.
 6. A dragline as set forthin claim 4 wherein said transmission includes an input end housingrotatably supporting said input shaft, an input pinion fixed to saidinput shaft for common rotation therewith, a reduction gear supported bysaid input end housing for rotation relative thereto about said centeraxis, said reduction gear being driven by said input pinion, a sun gearfixed to said reduction gear for common rotation therewith about saidcenter axis, a ring gear fixed to said input end housing and centered onsaid center axis, a plurality of planet gears which are driven by saidsun gear, which mesh with said ring gear and which revolve around saidcenter axis, and a carrier connected to said planet gears by respectivepins such that revolution of said planet gears around said center axiscauses rotation of said carrier about said center axis, and wherein saidcarrier drives said transmission output shaft.
 7. A dragline as setforth in claim 6 wherein said transmission output shaft has inner andouter ends, said inner end of said transmission output shaft beingspline fit to said carrier for common rotation of said transmissionoutput shaft with said carrier, wherein said pedestal also includes anoutboard leg which is spaced from said first-mentioned leg and which hastherein an outboard bore centered on said center axis, and wherein saiddragline further comprises an output pinion which drives said walk leghousing and which is mounted on said transmission output shaftintermediate said inner and outer ends thereof for common rotationtherewith, and a bearing capsule housed in said outboard bore, saidbearing capsule rotatably supporting said outer end of said transmissionoutput shaft.
 8. A dragline as set forth in claim 7 wherein said walkingmechanism also includes a driven gear rotatably supported by said mainhousing for rotation relative thereto about a generally horizontaldriven gear axis, said driven gear being driven by said output pinion,and a driven eccentric which is supported by said main housing forrotation relative thereto about said driven gear axis, which is drivenby said driven gear, and which drives said walk leg housing.
 9. Adragline as set forth in claim 8 wherein said walk leg housing isconnected to said driven eccentric and connected to said main housing bya knee link such that rotation of said driven eccentric causes walkingmovement of said walk leg housing.
 10. A dragline as set forth in claim1 wherein said transmission includes a fluid-tight transmission housingadapted to contain lubrication fluid.
 11. A dragline comprisinga mainhousing, a bucket hoist mechanism mounted on said housing, a bucket dragmechanism mounted on said main housing, a moving mechanism for movingsaid main housing over the ground, said moving mechanism including amotor mounted on said main housing, a planetary transmission which ismounted on said main housing, which has a generally horizontal centeraxis, and which is driven by said motor, a pedestal which is mounted onsaid main housing and which has therein a circular bore centered on saidaxis, and a pilot member including an annular projection housed in saidbore, said pilot member being fixed to said transmission, a boomextending from said main housing, a bucket, a hoist rope extendingbetween said bucket and said bucket hoist mechanism and over said sheavefor causing vertical movement of said bucket, and a drag rope extendingbetween said bucket and said bucket drag mechanism for causinghorizontal movement of said bucket.
 12. A dragline as set forth in claim11 wherein said pilot member also includes an annular flange extendingradially outwardly from said annular projection, said flange being fixedto said pedestal and to said transmission.
 13. A dragline as set forthin claim 11 and further comprising a cradle fixed to said planetarytransmission and to said main housing for supporting said transmissionabove said main housing.
 14. A dragline as set forth in claim 11 whereinsaid motor includes an output shaft rotatable about a generallyhorizontal axis, and wherein said dragline further comprises a planetarytransmission input shaft which is generally coaxial with said motoroutput shaft and which drives said transmission, and a spacer drivinglyconnecting said motor output shaft to said planetary transmission inputshaft.
 15. A dragline as set forth in claim 14 wherein said spacer isremovable from said motor output shaft and from said transmission inputshaft such that said transmission is moveable inwardly toward said motorto disengage said pilot member from said bore so that said transmissioncan thereafter be lifted relative to said main housing.
 16. A draglineas set forth in claim 14 wherein said transmission includes an input endhousing rotatably supporting said input shaft, an input pinion fixed tosaid input shaft for common rotation therewith, a reduction gearsupported by said input end housing for rotation relative thereto aboutsaid center axis, said reduction gear being driven by said input pinion,a sun gear fixed to said reduction gear for common rotation therewithabout said center axis, a ring gear fixed to said input end housing andcentered on said center axis, a plurality of planet gears which aredriven by said sun gear, which mesh with said ring gear and whichrevolve around said center axis, and a carrier connected to said planetgears by respective pins such that revolution of said planet gearsaround said center axis causes rotation of said carrier about saidcenter axis.
 17. A dragline as set forth in claim 16 wherein saidprojection surrounds and rotatably supports said carrier.
 18. A draglineas set forth in claim 16 wherein said ring gear, said input end housing,and said pilot member cooperate to define a fluid-tight transmissionhousing adapted to contain lubrication fluid.
 19. A dragline as setforth in claim 16 and further comprising a transmission output shafthaving inner and outer ends, said inner end of said transmission outputshaft being spline fit to said carrier for common rotation of saidtransmission output shaft with said carrier, wherein said pedestal alsoincludes an outboard leg which has therein an outboard bore centered onsaid center axis, and wherein said dragline further comprises an outputpinion mounted on said transmission output shaft intermediate said innerand outer ends thereof for common rotation therewith, and a bearingcapsule housed in said outboard bore, said bearing capsule rotatablysupporting said outer end of said transmission output shaft.
 20. Adragline comprisinga main housing, said main housing having a generallyhorizontal, upwardly facing surface, a bucket hoist mechanism mounted onsaid housing, a bucket drag mechanism mounted on said main housing, awalking mechanism for moving said main housing over the ground, saidwalking mechanism includinga motor mounted on said main housing floor,said motor including an output shaft rotatable about a generallyhorizontal axis, a planetary transmission input shaft generally coaxialwith said motor output shaft, a spacer drivingly connecting said motoroutput shaft to said planetary transmission input shaft, a planetarytransmission having a generally horizontal center axis and includinganinput end housing rotatably supporting said input shaft, an input pinionfixed to said input shaft for common rotation therewith, a reductiongear supported by said input end housing for rotation relative theretoabout said center axis, said reduction gear being driven by said inputpinion, a first sun gear fixed to said reduction gear for commonrotation therewith about said center axis, a first ring gear fixed tosaid input end housing and centered on said center axis, a plurality offirst planet gears which are driven by said sun gear, which mesh withsaid ring gear and which revolve around said center axis, a firstcarrier connected to said planet gears by respective pins such thatrevolution of said planet gears around said center axis causes rotationof said carrier about said center axis, a second sun gear fixed to saidfirst carrier for common rotation therewith, a second ring gear fixed tosaid first ring gear and centered on said center axis, a plurality ofsecond planet gears which are driven by said second sun gear, which meshwith said second ring gear and which revolve around said center axis, asecond carrier connected to said second planet gears by respective pinssuch that revolution of said second planet gears around said center axiscauses rotation of said second carrier about said center axis, a cradlefixed to said input end housing and to said main housing for supportingsaid input end housing above said main housing floor, a pedestal fixedto said main housing floor, said pedestal including inboard and outboardlegs extending upwardly from said main housing floor, said legs beingspaced in the direction of said center axis, said inboard leg havingtherein a circular inboard bore, and said outboard leg having therein acircular outboard bore, said bores being centered on said center axis, apilot member including an annular projection housed in said inboardbore, said pilot member also including an annular flange extendingradially outwardly from said annular projection, said flange being fixedto said inboard leg of said pedestal and to said second ring gear, saidprojection surrounding and rotatably supporting said second carrier, atransmission output shaft having inner and outer ends, said inner end ofsaid transmission output shaft being spline fit to said second carrierfor common rotation of said transmission output shaft with said secondcarrier, an output pinion mounted on said transmission output shaftintermediate said inner and outer ends thereof for common rotationtherewith, a bearing capsule housed in said outboard bore, said bearingcapsule rotatably supporting said outer end of said transmission outputshaft, a driven gear rotatably supported by said main housing forrotation relative thereto about a generally horizontal driven gear axis,said driven gear being driven by said output pinion, a driven eccentricwhich is supported by said main housing for rotation relative theretoabout said driven gear axis and which is driven by said driven gear, awalk leg housing connected to said driven eccentric and connected tosaid main housing by a knee link such that rotation of said driveneccentric causes walking movement of said walk leg housing, and a shoefixed to said walk leg housing for engaging the ground during walkingmovement of said walk leg housing, said spacer being removable from saidmotor output shaft and from said transmission input shaft such that saidtransmission is moveable inwardly toward said motor to disengage saidpilot member from said inboard bore after said flange is disconnectedfrom said inboard leg, so that said transmission can thereafter belifted relative to said main housing floor, a boom extending from saidmain housing, a bucket, a hoist rope extending between said bucket andsaid bucket hoist mechanism and over said sheave for causing verticalmovement of said bucket, and a drag rope extending between said bucketand said bucket drag mechanism for causing horizontal movement of saidbucket.